Spinal-column distractor

ABSTRACT

A spinal-column distractor ( 10 ) comprises a first pusher plate ( 1 ) intended to bear on a vertebra, a second pusher plate ( 2 ) intended to bear on an adjacent vertebra, and a slide ( 3 ). The slide ( 3 ) is connected to the first pusher plate ( 1 ) via a scissor linkage ( 4 ), and shiftable by a threaded spindle to change a spacing between the first pusher plate ( 1 ) and the second pusher plate ( 2 ), while the second pusher plate ( 2 ) forms a track for the slide ( 3 ).

The present invention relates to a spinal-column distractor, and inparticular concerns a spinal-column distractor with a first pusher platefor bearing on a vertebra and a second pusher plate for bearing on anadjacent vertebra.

Various spinal-column distractors are already known from the prior art.However, the disadvantage of previously known distractors is that asurgeon has difficulty handling them.

Thus, the object of the invention is to develop a spinal-columndistractor of the above-described type is easier to manipulate duringsurgery.

According to a first feature of the present invention this object ofproviding a spinal-column distractor with a first pusher plate intendedto bear on a vertebra and a second pusher plate intended to bear on anadjacent vertebra is attained by connecting a slide to the first pusherplate via a scissor linkage, with the slide shiftable by a threadedspindle to change the spacing between the first pusher plate and thesecond pusher plate. The second pusher plate forms a track for theslide. This embodiment has the advantage that distraction of thevertebrae can be precisely adjusted in a simple manner.

Preferably, the threaded spindle comprises a coupling configured toconnect with an insertion instrument. This makes it easier to operatethe distractor by the insertion instrument. It proved to be advantageousfor the coupling to have coupling notches that are embodied forengagement with teeth of the insertion instrument. It turned out to beparticularly advantageous for the coupling notches to be formed as amultitooth coupling, particularly as a crown gear.

In a preferred illustrated embodiment of the distractor according to thepresent invention the first pusher plate has a bevel in an end facingaway from and opposite the coupling. This facilitates the insertion ofthe distractor between the vertebral bodies of the spinal column.

Further, a groove to guide the holder of the insertion instrument may beformed on one longitudinal side of the distractor, particularly on bothlongitudinal sides of the second pusher plate, thereby increasingstability to stresses.

Moreover, the first pusher plate may be shaped to receive a spacer blockintended to bear on a vertebra, so that the achievable distraction areacan be flexibly adjusted by spacers of different heights.

The insertion instrument may further comprise a holder adapted tosupport the second pusher plate, thereby increasing stability. Forbetter manageability the insertion instrument may further comprise apositioning rod.

According to a third feature of the present invention, for a distractionsystem this object is attained by a combination of one of theabove-described distractors with one of the above-described insertioninstruments.

In the following the invention is explained in greater detail based onan illustrated embodiment shown in the drawing:

FIG. 1 is a schematic perspective view of a distractor according to thepresent invention,

FIG. 2 is an illustration of the distractor from FIG. 1 coupled with aninsertion instrument,

FIG. 3 a is a schematic overview of a combination of the distractor withthe insertion instrument according to the invention in a distractionposition in which the pusher plates are at the furthest spacing fromeach other, and

FIG. 3 b is an enlarge view of the detail indicated at Z in FIG. 3 a.

FIG. 1 is a schematic perspective view of a spinal-column distractor 10.The distractor 10 comprises a first pusher plate 1 intended to bear onone vertebra, a second pusher plate 2 intended to bear on an adjacentvertebra, and a slide 3. The slide 3 is connected to the first pusherplate 1 via a scissor linkage 4 and can shift to change the spacingbetween the first pusher plate 1 and the second pusher plate 2 via athreaded spindle, with the second pusher plate 2 formed as a track forthe slide 3. This way, the distractor 10 can be distracted or shorteneddepending on the rotation direction.

The distractor 10 has a coupling 5 formed with coupling notches 7. Thescissor linkage 4 may further comprise a guide rod 13 slidable in aguide slot 14 of the first pusher plate 1 when the scissor linkage 4 ismoved. In addition, guiding slide 3 in a dovetail track on the secondpusher plate 2 can make a more even and gentler distraction possible.Here nuts 12 secure the slide 3 on the scissor linkage 4. The secondpusher plate 2 may further be formed with a bevel 8 at the end facingaway from and opposite the coupling 8.

FIG. 2 schematically shows the connection of the distractor 10 with aninsert instrument 20. For coupling, the distractor 10 is fitted to aholder 6 with the aid of a positioning rod 11. Engagement teeth of theinsertion instrument 20 engage with coupling notches 7 of a coupling 5of the distractor 10. The distractor 10 can then be inserted into theintervertebral space by the holder 6. The insertion instrument 20 cancarefully spread the distractor 10 until the desired distraction isachieved. By detaching the positioning rod 11 the holder 6 can beseparated from the distractor 10, and the distractor 10 can remain insitu. After surgery the distractor 10 can be fitted to the holder 6again and held by the positioning rod 11. By reverse rotating theinsertion instrument 20 the distractor 10 can be shortened again, andthus removed from the intervertebral space.

For a better understanding FIG. 3 a shows a total overview of adistraction system 100 comprising the distractor 10 and the insertioninstrument 20. A hand wheel 15 on the insertion instrument 20 serves foraccurately controlling the distraction.

FIG. 3 b shows a detailed and enlarged view of the Z detail of thedistractor 10 from FIG. 3 a, in which the first pusher plate 1 is atmaximum spacing from the second pusher plate 2. To get a greaterdistraction, attachments of various heights can be mounted on the pusherplate 2.

REFERENCE NUMBER LIST

-   1 first pusher plate intended to bear on a vertebra-   2 second pusher plate intended to bear on a vertebra-   3 slide-   4 scissor linkage-   5 coupling-   6 holder-   7 coupling groove-   8 bevel of the second pusher plate-   9 guide groove to guide the holder-   10 distractor-   11 positioning rod-   12 nuts to attach the slide-   13 slide guide rod-   14 guide slot in the first pusher plate-   15 hand wheel-   20 insertion instrument-   100 distraction system

1. A spinal-column distractor comprising a first pusher plate intendedto bear on one vertebra, a second pusher plate intended to bear on anadjacent vertebra, a slide, a scissor linkage connecting the slide tothe first pusher plate, and a threaded spindle connected to the slidefor shifting same to change a spacing between the first pusher plate andthe second pusher plate, the second pusher plate being formed as a trackfor the slide.
 2. The distractor in accordance with claim 1 wherein thethreaded spindle is provided with a coupling constructed for connectionwith an insertion instrument.
 3. The distractor in accordance with claim2 wherein the coupling comprises coupling notches designed forengagement with teeth of the insertion instrument.
 4. The distractor inaccordance with claim 3 wherein the coupling notches form a multi-toothcoupling.
 5. The distractor in accordance with claim 2 wherein the firstcontact pate has a bevel in an end facing away from and opposite thecoupling.
 6. The distractor in accordance with claim 2 wherein a guidegroove for a holder of the insertion instrument is formed on one bothlongitudinal sides of the second pusher plate.
 7. The distractor inaccordance with claim 1 wherein the first pusher plate is shaped toreceive a spacer block.
 8. The distractor in accordance with claim 1wherein the slide is guided in a dovetail groove.
 9. The distractor inaccordance with claim 1 wherein the first pusher plate has a guide slotto receive a guide rod of the slide.
 10. An insertion instrumentcomprising a hollow shaft and a drive rod for coupling to a distractorin accordance with claim
 1. 11. The insertion instrument in accordancewith claim 10 wherein the insertion instrument comprises a holder shapedto hold the second pusher plate.
 12. The insertion instrument inaccordance with claim 10 wherein the insertion instrument comprises apositioning rod.
 13. A combination of the distractor in accordance withclaim 1 and an insertion instrument comprising: a hollow shaft and adrive rod for coupling to the distractor.